In the field of photomechanical process, there are demands for satisfactory image reproducibility, stability of processing solutions, and simplification of replenishment in order to cope with the recent diversity and complexity of printed materials.
In particular, originals in line work are comprised of photo-composed letters, hand-written letters, illustrations, dot prints, etc. and thus contain images having different densities or line widths. It has been therefore keenly demanded to develop a process camera, a photographic light-sensitive material or an image formation system which enables us to reproduce the original with good reproducibility. In the photomechanical process of catalogues or large posters, on the other hand, enlargement or reduction of a dot print is widely conducted. When a dot print is enlarged in plate making, the line number becomes small and the dots are blurred. When a dot print is reduced, the line number/inch becomes larger and the dots become finer than the original. Accordingly, an image formation system having a broader latitude has been demanded for maintaining reproducibility of halftone gradation.
A halogen lamp or a xenon lamp is employed as a light source of a process camera. In order to obtain photographic sensitivity to these light sources, photographic materials are usually subjected to orthochromatic sensitization. However, it turned out that orthochromatic materials are more susceptible to influences of chromatic aberration of a lens and thus liable to image quality deterioration. The deterioration is conspicuous in using a xenon lamp as a light source.
Known systems meeting the demand for a broad latitude include a method comprising processing a lith silver halide light-sensitive material comprising silver chlorobromide (containing at least 50% of silver chloride) with a hydroquinone developer having an extremely low effective sulfite ion concentration (usually 0.1 mol/l or less) to thereby obtain a line or dot image having high contrast and high density in which image areas and non-image areas are clearly distinguished. According to this method, however, development is extremely unstable against air oxidation due to the low sulfite concentration of the developer. Hence, various efforts and devices are required to stabilize the developing activity and, also, under the present situation, the processing speed is considerably low to reduce working efficiency.
It has thus been demanded to establish an image formation system which eliminates the image formation instability associated with the above-described lith development system and provides a ultrahigh contrast image by using a processing solution having satisfactory preservation stability. In this connection, it has been proposed to develop a surface latent image type silver halide photographic material containing a specific acylhydrazine compound with a developing solution having a pH between 11.0 and 12.3 and containing at least 0.15 mol of a sulfite preservative and thereby exhibiting satisfactory preservation stability to form a ultrahigh contrast negative image having a gamma exceeding 10, as disclosed in U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,272,606, and 4,311,781. This new image formation system is characterized in that silver iodobromide and silver chloroiodobromide as well as silver chlorobromide are applicable thereto, whereas the conventional ultrahigh contrast image formation systems are only applicable to photographic materials comprising silver chlorobromide of high silver chloride content.
While the above-described image formation system exhibits excellent performance in dot quality, stability of processing, and rapidness of processing, there are disadvantages, such as poor reproducibility of line originals, poor reproducibility in reduction or enlargement work, and large dependence on light source, and improvements on these points have been demanded.
In the above-described image formation system, exposure through a filter has been adopted for various purposes as disclosed, e.g., in JP-A-62-210458, JP-A-63-104046, JP-A-63-103235, JP-A-63-95438, JP-A-63- 95435, JP-A-63-95437, JP-A-63-306436, and JP-A-64-55549. However, application of any of these methods is limited to light-sensitive materials for bright room processing containing no orthochromatic sensitizing dyes.
Image formation systems of using hydrazine derivatives have been proposed to obtain a high contrast image while using a stable developer as disclosed in U.S. Pat. Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, 4,211,857, and 4,243,739. According to these systems, ultrahigh contrast and high sensitivity can be obtained. Further, since use of a developer containing a sulfite in a high concentration is permissive, stability of the developer against air oxidation can be greatly improved over lith developers. Nevertheless, it has turned out that the systems using hydrazine derivatives tend to cause a phenomenon called black pepper.
The terminology "black pepper" as used herein means black spots appearing in non-image areas (for example, between dots). The black pepper phenomenon conspicuously takes place when a sulfite ion concentration commonly employed as a preservative is reduced or the pH of the developer increases due to fatigue of a developer with time and causes impairment of image quality.
Use of certain kinds of shorter wavelength sensitizing dyes to eliminate black pepper is disclosed in JP-A-62-237445, JP-A-62-280733, JP-A-01-61743, JP-A-01-61744, JP-A-01-92738, and JP-A-01-217339.